Secondary (rechargeable) lithium ion batteries are used in many applications including automotive, mobile electronic devices, and small or large electrical energy storage systems. In contrast with conventional lithium ion battery systems, the electrodes in new lithium ion batteries, such as Li/S batteries, are composed of abundant elements and therefore promise to be lower cost than conventional batteries. Additionally, Li/S batteries offer higher specific energy and energy density at similar or better performance. However, commercialization has been hindered by performance limitations and practical manufacturing challenges.
One challenge still hindering the practical development of Li/S batteries is the high solubility of the polysulfides in conventional electrolytes. The dissolving of the polysulfides leads to poor battery properties (e.g., a loss of capacity upon repeated cycling). One mechanism by which the degradation can occur is the dissolved polysulfide anions can migrate through the electrolyte and reach the anode, where they react to form insoluble products on its surface and impede battery operation.
Conventional lithium ion batteries (with conventional cathode and anode materials) have insufficient battery characteristics such as battery life and performance. For example, sulfur-containing cathode materials tend to have low conductivity, and therefore conductive carbon is typically added to the cathode to increase the electrical conductivity. In cases where lithium-sulfur batteries use elemental Li metal in the anode, the resulting batteries tend to have poor electrical cycling performance and stability.